1. Field of the Invention
This invention relates to a control system, for operating adjustable automotive suspension units, which has the ability to adapt to impairment of the adjustable feature of the suspension units.
2. Disclosure Information
Multistable automotive suspension units have been known for some time. Such suspension units are typically mounted between the sprung and unsprung portions of the vehicle. Suspension units defined as "multistable" have the ability to be operated in a plurality of predetermined states. Such suspension units are intended to provide control of vehicle ride and handling which may be tailored to particular road surfaces and/or driver characteristics. In typical fashion, the particular state chosen for the multistable unit is determined by a control algorithm with inputs from a variety of vehicle parameters. For example, it is known to control a multistable suspension unit by utilizing vehicle linear acceleration, braking, steering activity, and vehicle speed as well as through a manually operable mode switch. U.S. Pat. No. 4,621,833 discloses a system for operating multistable suspension units, including feedback of the operating mode of each suspension unit.
U.S. Pat. No. 4,700,303 discloses a system for operating a vehicle height adjusting apparatus in the event that an abnormality is detected in the sensors which measure the vehicle's ride height. If such abnormality is detected, the control system will operate a compressor until a minimum pressure is produced in an air suspension system. Similarly, it is known to compensate for loss of the ability to control one or more of the suspension units in an automotive vehicle by placing all of the units into a predetermined control position. U.S. Pat. Nos. 4,526,401 and 4,666,180 disclose two control systems in which the inability to operate adjustable suspension units is compensated for by the placement of all the operational suspension units into a "normal" damping force condition. Although such control systems may cope with the loss of control of a suspension unit to a certain extent, the control schemes set forth in the '303, '401 and '180 patents are not adaptive inasmuch as they lack the capability of selecting an operating mode for any viable suspension units which operating mode takes into account the specific nature of the inability to adjust one or more of the remaining suspension units. Too, such systems do not provide for the contingency that the "normal" adjustment position may not be attainable.
It is an object of the present invention to Provide an adaptive control system for operating adjustable automotive suspension units having the ability to detect units which are not capable of being fully operated and to evaluate the extent to which the ability to operate such units has been impaired, and having done so, to select an operating position for each of the operable suspension units.
It is an advantage of the present invention that a control system according to this invention will minimize the degradation of ride control of a vehicle in the event that one or more of the adjustable suspension units becomes inoperative.
Other objects, features and advantages of the present invention will become apparent to those skilled in the art to which is invention pertains.